In recent years, a reduction in mass of railcars has been demanded with an increase in speed of the railcars, and railcars that are improved in comfort of passengers, such as ride quality, have been strongly demanded. In response to these, known is a railcar bodyshell that is improved in the ride quality by reducing the sizes of side windows to increase bending stiffness of the bodyshell.
Known as one of the structures of side bodyshells of railcars is a double skin structure using an aluminum alloy hollow extruded section constituted by two face plates and ribs each coupling these face plates to each other. The reduction in mass and the improvement in ride quality of the railcar having the above structure have also been demanded. In response to these, PTL 1 proposes a railcar bodyshell configured such that only the thickness of a face plate of a hollow section constituting a pier panel that is a portion between windows of the side bodyshell is uniformly increased in a railcar longitudinal direction as compared to the thickness of a face plate of the other hollow section constituting the side bodyshell. PTL 1 describes that the railcar bodyshell that is high in bending stiffness and light in mass can be provided by the above configuration.